Suppression circuit

ABSTRACT

A suppression circuit, in particular for suppressing the noise of the wiper motor of a motor-vehicle, is provided with at least two capacitors ( 4, 5 ), which are situated between one common ( 1 ) terminal and two separate terminals ( 2, 3 ), and it is provided with pulse limitation. For purposes of pulse limitation, each capacitor has connected to it in parallel the series circuit composed of the cathode-anode path of a diode ( 6, 7 ) and of the anode-cathode path of a Zener diode ( 8 ). The suppression circuit according to the present invention, in one advantageous application, can be embedded as a suppression module in a suppression device, which is provided in a capacitor enclosure. The capacitor enclosure has three contact terminals, which stand in a fixed spatial relationship to each other, irrespective of the number of suppression components, and it can be block-like or cuboid in shape.

BACKGROUND INFORMATION

The present invention relates to a suppression circuit, in particularfor suppressing the noise of the wiper motor of a motor vehicle, thesuppression circuit being provided with at least two capacitors, whichare situated between one common terminal and two separate terminals, italso being provided with pulse limitation, of the species defined in thepreamble of claim 1.

From the German Design Patent 2 96 19 780.7, a suppression device isknown for suppressing the noise of the wiper motor of a motor vehicle.In this context, the suppression circuit contains two capacitors, whichare situated between one common and two separated terminals.Furthermore, to improve the suppression, pulse limitation is provided,which is realized by a varistor parallel to each capacitor.

A varistor is a relatively expensive component requiring considerablespace. It is known that the limiting function of the varistor, withrespect to the positive and negative voltage pulses, can also berealized by an anti-serial circuit arrangement having two Zener diodes.Components of this type combined in one enclosure are known and areavailable as bidirectional Zener diodes. However, as a result of thecomparatively low quantities in comparison with standard, conventionalcomponents, such as diodes and Zener diodes, their price isdisproportionately high.

ADVANTAGES OF THE INVENTION

In contrast, the suppression circuit according to the present invention,in particular for suppressing the noise of the wiper motor of a motorvehicle, having the characterizing features of claim 1, has theadvantage of making available a simple and reliable solution in whichthe costs are reduced and lower space requirements are achieved. Thenumber of soldering or welding points, of points of connectiongenerally, is small, so that in addition to the advantage of usingcost-effective components such as Zener diodes and diodes, the advantageof a simpler production process is also achieved. As a result of thefact that the number of points of connection is reduced, the sources oferrors arising in soldering or welding are also significantly reduced.

In the suppression circuit according to the present invention, for thegeneral purpose of pulse limitation, the series circuit composed of thecathode-anode path of a diode and the anode-cathode path of a Zenerdiode is connected in parallel to each capacitor. In this context, foruse in a motor, the component facing the negative terminal clamp is theZener diode having its cathode. With respect to the positive terminalclamp, the blocking effect of a simple diode is exploited, the cathodeof the diode being connected to the terminal.

As result of the measures laid down in the further claims, advantageousrefinements and improvements of the suppression circuit indicated inclaim 1 are possible.

According to one particularly expedient refinement of the presentinvention, it is provided that the anodes of the diodes and of the Zenerdiode are connected together at one point.

In one preferred, advantageous embodiment of the suppression circuitaccording to the present invention, in using two capacitors, a singleZener diode is provided for both parallel circuits. In this manner, aversion is created that is very simple and, in practice, verycost-effective and space-saving.

In one particularly advantageous and expedient refinement of the presentinvention, it is embedded, as a suppression module, in a suppressiondevice, which is provided in a capacitor enclosure. In accordance withone advantageous embodiment of this refinement of the present invention,the capacitor enclosure has three contact terminals, which stand in afixed spatial relationship to each other, irrespective of the number ofsuppression components. In a further embodiment, the capacitor enclosurehas a block-like or cuboid shape.

DRAWING

The present invention is discussed in greater detail in the followingdescription on the basis of the exemplary embodiment depicted in thedrawing. The single Figure, in a block diagram, schematically depictsthe design of the suppression circuit according to the presentinvention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

In FIG. 1, the design of the suppression circuit according to thepresent invention is given a schematic representation. The suppressionmodule, designated as reference numeral 10, has three terminals 1, 2,and 3. At terminal 1, for example, a negative potential is applied, andat terminals 2 and 3 a positive potential. Between terminals 1 and 2, aswell as between 1 and 3, in each case, one capacitor 4, 5, respectively,is arranged. According to the present invention, for the purpose ofpulse limitation, parallel to each capacitor 4 and 5, the series circuitis connected in parallel made of the cathode-anode path of a diode 6 and7, respectively, and of the anode-cathode path of a Zener diode 8. Theanodes of diodes 6 and 7 and of Zener diode 8 are connected together atone point 9.

In the depicted example, only one single Zener diode 8 is provided. Thissaves on one separate Zener diode. However, it is possible, and in somecases necessary or advantageous, to connect, in each case, a completeseries circuit composed of two components, diode and Zener diode, inparallel to one capacitor. In this context, it is then advantageous, butnot absolutely necessary, to connect the anodes of the diodes and of theZener diodes at one point. It is also possible to insert a separatecapacitor between both terminals 2 and 3, in order to increase thesuppression effect, if desired. This is not depicted in FIG. 1.

According to one especially advantageous and expedient refinement of thepresent invention, it is embedded as a suppression module in asuppression device, which is provided in a capacitor enclosure. In anadvantageous embodiment of this refinement of the present invention, thecapacitor enclosure has three contact terminals, which stand in a fixedspatial relationship to each other, irrespective of the number ofsuppression components. The capacitor enclosure is advantageouslyblock-like or cuboid in shape.

This embodiment, and use, of the suppression circuit according to thepresent invention, not depicted in the Figure, brings with it furtherproduction-technical simplifications and economies.

What is claimed is:
 1. A suppression circuit for suppressing a noise ofa wiper motor of a motor vehicle, comprising: one common terminal; twoseparate terminals; at least two capacitors situated between the onecommon terminal and the two separate terminals; and a series circuitincluding a cathode-anode path of a diode and an anode-cathode path of aZener diode, the series circuit being connected in parallel to each ofthe capacitors, for providing a pulse limitation.
 2. The suppressioncircuit according to claim 1, wherein anodes of the diode and of theZener diode are connected together at one point.
 3. The suppressioncircuit according to claim 1, wherein the at least two capacitorsinclude only two capacitors and wherein the Zener diode includes onlyone Zener diode.
 4. The suppression circuit according to claim 1,wherein the suppression circuit is embedded as a suppression module in asuppression device situated in a capacitor enclosure.
 5. The suppressioncircuit according to claim 4, wherein the capacitor enclosure has threecontact terminals, which stand in a fixed spatial relationship to eachother, irrespective of a number of suppression components.
 6. Thesuppression circuit according to claim 4, wherein the capacitorenclosure is one of block-like and cuboid in shape.